In recent years, the Internet has been heavily used, and several types of packets including voice packets or video packets are transmitted and received through the Internet. The transmission and reception of voice packets or video packets are greatly affected by delays due to congestion or data loss. For this reason, it is desired that the communication quality be improved. However, a best effort system is adopted on the Internet, and all data is handled equally when an excessive amount of data flows into one communication line. Hence, when the amount of data that is transmitted and received exceeds the capacity of the communication line, the communication quality deteriorates.
Accordingly, a communication network called the Next Generation Network (NGN) has been provided by telecommunications carriers. The NGN is operated by using the guarantee system, which guarantees communication quality such as a minimum communication speed, and the communication quality is managed by using a quality of service (QoS) parameter. For this reason, when a voice packet or the like that includes a QoS parameter is transferred through the NGN, voice data or the like is transferred at a certain quality.
As described above, both the Internet and the NGN are provided, and thus a packet may be transferred from the Internet to the NGN. When a packet is transferred from the Internet to the NGN, the communication quality is not managed even in the NGN and data is transferred with the best effort system unless a QoS parameter is set that supports the management of the communication quality in the NGN.
As a system used when there are services existing in parallel that are operated by different schemes, a communication system that provides Internet Protocol Multimedia Subsystem (IMS) service and non-IMS service is known. In that system, a control server connected to the network refers to a resource control device for resource permission information when receiving a service request, and accepts the service request when permitted. The resource control device transmits the permitted policy information to an access gateway device, and the access gateway device performs priority control or the like by using the received policy information. Also, a protocol such as a HyperText Transfer Protocol (HTTP) is used to transmit and receive data between a server and a browser.